Learn Hardcore Korean: yeonhyu saebyeogeneun doroga wiheomhanikka cheoncheonhi ga. - Since roads are dangerous at dawn during long weekends, go slowly.

연휴: a span of consecutive holidays (long weekend/holiday period).
새벽: pre-dawn/early morning, roughly from after midnight until around sunrise.
에는: combination of the time/location particle 에 (“at/on/in”) plus the topic/contrast marker 는. Together, 새벽에는 means “as for (at) dawn,” often with a contrastive or generalizing nuance.

Why use 에는 instead of just 에?

Adding 는 topicalizes and often contrasts that time frame with others.

연휴 새벽에 = at dawn during the holiday (neutral).
연휴 새벽에는 = as for dawns during the holiday (implies contrast/emphasis: that time in particular).

Can I say 연휴의 새벽에는 or contract it to 연휴 새벽엔?

연휴의 새벽에는 is grammatically fine but feels more formal/bookish. In everyday speech, Koreans often drop 의 and use the noun-noun sequence: 연휴 새벽에는.
The colloquial contraction 에는 → 엔 is common in speech: 연휴 새벽엔.

Why is it 도로가 with the subject marker 가, not 도로는?

도로가 위험하다 states a fact about the road(s) being dangerous; 가 marks the grammatical subject naturally here.
도로는 위험하다 would topicalize/contrast the road with something else (e.g., “The road is dangerous, but the subway isn’t”). In this sentence, no such contrast is implied, so 가 is the default.

Why not say 도로에서 위험하니까?

도로가 위험하다 describes the road as dangerous (adjective predicate + subject).
도로에서 위험하다 means “it’s dangerous on the road,” but then you usually need a subject for what is dangerous (e.g., 도로에서 운전하는 게 위험하니까 “since driving on the road is dangerous”). Without that gerund phrase, 도로에서 위험하다 sounds incomplete.

Why use the connector -니까 instead of -아서/어서?

With commands or suggestions, Korean prefers -니까 to present the reason.

Natural: 위험하니까 천천히 가.
Generally avoided with commands: 위험해서 천천히 가. (sounds off/less standard in this usage)

Could I use -기 때문에 instead?

In cause-result statements, -기 때문에 is fine, but it’s typically avoided before commands/suggestions in conversation.

More formal, and can feel awkward here: 위험하기 때문에 천천히 가.
Stick with -니까 for giving advice/commands: 위험하니까 천천히 가.

How strong or polite is 천천히 가?

It’s the intimate/plain imperative (casual). Use it with close friends, family, or someone younger. More polite options:

천천히 가요. (polite)
천천히 가세요. (polite honorific; respectful advice)
Very formal: 천천히 가십시오.

Does 가다 here really mean “drive,” not just “go”?

Literally it’s “go,” but in context (talking about roads), it naturally means “drive/go (by car).” If you want to be explicit:

천천히 운전해. (Drive slowly.)
조심히 운전하세요. (Drive carefully.)

Can I rearrange the time phrases?

Yes, but keep them clear and natural.

Original is compact and idiomatic: 연휴 새벽에는 도로가… (holiday-dawn as one time frame)
Also possible: 연휴에 새벽에는 도로가… (both time markers; acceptable, slightly heavier)
Avoid doubling topics awkwardly: 연휴에는 새벽에는… is clunky.
You can also split into two sentences: 연휴에는 도로가 위험해. 새벽에는 더 그래.

How is the whole sentence pronounced naturally?

연휴 새벽에는 → [연휴 새벼게는] (liaison: 새벽+에 → 새벼게)
도로가 → [도로가]
위험하니까 → [위험하니까]
천천히 → [천천히] (often sounds like [천처니] in fast speech)
가 → [가]

What’s the difference between 천천히 and 느리게?

천천히: “slowly, at an easy/careful pace” and is what you naturally say to a person as advice: 천천히 가/하세요.
느리게: “slowly” in a more descriptive/speed sense; common in narration: 차가 느리게 간다. As a command to a person, 느리게 가 is less idiomatic than 천천히 가.

Could I nuance the reason with “gets” or “probably”? Like 위험해지니까 or 위험할 테니까?

Yes:

위험해지니까 = “since it gets/becomes dangerous.”
위험할 테니까 = “since it’s probably going to be dangerous.”
Both are natural with commands: …천천히 가.

What’s the difference between 도로 and 길?

도로: a roadway for vehicles (streets, highways).
길: any path/way (can be a road, a path, “the way”). In traffic/safety contexts, 도로 is more specific and natural.

Why is there no subject like 너는?

Korean often drops pronouns when they’re obvious from context. Here, the addressee is clear, so (너는) 천천히 가 becomes simply 천천히 가. Also, avoid 당신; it’s rarely used for “you” in everyday speech and can sound impolite.

Is there an even softer, more caring way to say the second part?

Yes:

천천히 가요. 조심히요.
조심해서 가세요. or 안전운전 하세요.
These sound warmer and more considerate.

Can I add emphasis like “especially” or “really”?

Sure:

연휴 새벽에는 도로가 특히 위험하니까 천천히 가.
연휴 새벽에는 도로가 정말 위험하니까 천천히 가.

Is there a handy two-sentence version using 그러니까?

Yes:

연휴 새벽에는 도로가 위험해. 그러니까 천천히 가.
This is very natural in speech: state the fact, then give the advice.

Is the spacing in 연휴 새벽에는 correct?

Yes. Keep a space between 연휴 and 새벽. It’s a noun–noun sequence (you could also write the more formal 연휴의 새벽). Writing it as one block (연휴새벽) is not standard.